The objective of this program is to identify general and specific mechanisms which elicit, channel and control aggression in primate groups. The basic approach is to monitor spontaneous occurrences in undisturbed groups and then to generate specific hypotheses to test with a set of manipulated groups. Systematic studies of animal introductions are used to reveal group coordination in agonistic encounters and to test the influence of age, sex, familiarity, species membership and seasonal factors as they influence agonistic responses. Inasmuch as male transfers between groups serve as the natural means of genetic exchange in wild populations of many primate species, we will test various types of prior manipulations of experience with a group prior to introduction in an attempt to discover the mechanism which allow for male transfer inasmuch as the strongest resistance to male introductions has been documented. We will also address ourselves to the question of rank and aggression, hoping to demonstrate the dependence of both upon a particular social situation. We plan to manipulate two groups such that the rank positions of males will be reversed in the two social contexts. Gonadal hormone responses to status changes and aggressive expressions and losses will be monitored both as effects and predisposing factors.